• Title/Summary/Keyword: Sol-gel preparation

Search Result 428, Processing Time 0.025 seconds

Preparation and Sinterability of Nano-Size $TiO_2$ Powders Using Supercritical Fluids (초임계 유체를 이용한 나노크기 $TiO_2$ 분말제조 및 소결특성)

  • 송정환;이정석;박인석;임대영
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.7
    • /
    • pp.625-631
    • /
    • 2000
  • In this study, the characteristics and sinterablities of TiO2 powders which were fabricated on sol-gel process and supercritical fluid process were examined. The powders fabricated on sol-gel process were amorphous. The particle size and shape were changed with the amount of water used for hydrolysis of titanium ethoxide. The powders were changed from amorphous to crystalline by heating at 400℃. The crystalline anatase TiO2 powders were directly prepared in ethanol supercritical fluid condition that temperature was 270±3℃ and pressure was 7.3 MPa. It's primary crystalline size was 20 nm and agglomerated as spherical shape whose size was 0.7∼1㎛. The powders prepared on sol-gel process were not sintered densely at 900℃ because of abnormal grain growth. However, the powders which prepared on supercritical fluid process were sintered densely at the comparatively low temperature of 800℃ by ideal growth of grain, which are fired at 900℃.

  • PDF

Peculiarities of amorphous and crystalline dielectric films prepared by sol-gel method

  • Natalya, Korobova;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2005.07a
    • /
    • pp.401-402
    • /
    • 2005
  • The important parts of material science in the film preparation fields and sol-gel technology are presented. For the present work, a series of amorphous films was prepared in air by sol-gel method without using some alkoxide stabilizer, which reduces the reactivity of the metal alkoxides. The choice of precursors can affect the chemical-reaction kinetics, microstructures and properties of the product. In this report author compared the crystallization behavior of oxide functional films derived from the same precursors, stressing the influence of experiment conditions and where it was possible to obtain the uniform amorphous or crystalline dielectric films. A short analysis of sol-gel technology and thin film methods about development of dielectric materials has been given.

  • PDF

Preparation of Silica Core-Hybrid Pigment via Sol-Gel Process and It's Application for Inkjet Dispersion Ink (졸-겔법을 이용한 실리카 핵을 가지는 하이브리드 안료의 제조와 잉크젯 분산 잉크로서 응용)

  • Jeon, Young-Min;Kim, Jong-Gyu;Gong, Myoung-Seon
    • Korean Journal of Materials Research
    • /
    • v.16 no.10
    • /
    • pp.599-605
    • /
    • 2006
  • N-(3-triethoxysilylpropyl)-1,4-diaminoanthrquinone-2,3-dicarboximide (TESP-DADI), an organic blue pigment, has been prepared and incorporated into silica solid matrix reacting triethyl orthosilicate (TEOS) via sol-gel method. Morphology and microstructure of resulting hybrid pigment were studied employing SEM and TEM. The micrographs and particle size distributions showed that uniform pigment can be obtained employing TEOS-based sol-gel method forming silica core. Particle size distribution of dispersed pigment in water was examined using the technique of dynamic light scattering. The ensuing pigment dispersion ink was subjected to various physicochemical evaluation such as viscosity, surface tension, inkjet stability, storage stability, and color change as inkjet ink using spectrophotometric, and microscopic techniques.

Preparation of Submicron YBaCuO Powder by Sol-gel Method

  • Fan, Zhanguo;Soh, Dea-Wha
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2003.07a
    • /
    • pp.557-560
    • /
    • 2003
  • The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to $1.0\;{\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)O_2$ and CuO. When pH values were adjusted to $6.4{\sim}6.7,\;Ba(NO_3)O_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. After the heat treatment the transition temperature($T_c$) and critical current density($J_c$) of the $YBa_2Cu_3O_x$ samples made of the submicron powder were measured.

  • PDF

Preparation of Barium Ferrite Thin Film by Sol-Gel Method (졸겔법을 이용한 바륨페라이트 박막 제조)

  • 변태봉;조원덕;김태옥
    • Journal of the Korean Ceramic Society
    • /
    • v.34 no.1
    • /
    • pp.37-44
    • /
    • 1997
  • Barium ferrite thin films on the thermal oxidized Si substrate were prepared by using sol-gel method (dip coating) from the sol of composition ratio of 5.25, designated by mole ratio 2Fe/Ba. The gelation process was largely divided into 4 step, and the sol prepared by reaction for 90 minutes at 8$0^{\circ}C$ was the suit-able for coating. Needle shaped particles formed on the coating layer were placed parallel to substrate and the inclination was increased with film thickness. The easy-direction of magnetization of needle shaped par-ticles was long-axis direction.

  • PDF

Preparation of CuO-CeO2 mixed oxide catalyst by sol-gel method and its application to preferential oxidation of CO (졸-겔법에 의한 CuO-CeO2 복합 산화물 촉매의 제조 및 CO의 선택적 산화반응에 응용)

  • Hwang, Jae-Young;Hahm, Hyun-Sik
    • Journal of the Korean Applied Science and Technology
    • /
    • v.34 no.4
    • /
    • pp.883-891
    • /
    • 2017
  • For the preferential oxidation of CO contained in the fuel of polymer electrolyte membrane fuel cell (PEMFC), CuO-$CeO_2$ mixed oxide catalysts were prepared by the sol-gel and co-precipitation methods to replace noble metal catalysts. In the catalyst preparation by the sol-gel method, Cu/Ce ratio and hydrolysis ratio were changed. The catalytic activity of the prepared catalysts was compared with the catalytic activity of the noble metal catalyst($Pt/{\gamma}-Al_2O_3$). Among the catalysts prepared with different Cu/Ce ratios, the catalyst whose Cu/Ce ratio was 4:16 showed the highest CO conversion (90%) and selectivity (60%) at $150^{\circ}C$. As the hydrolysis ratio was increased in the catalyst preparation, surface area increased, and catalytic activity also increased. The highest CO conversions with the CuO-$CeO_2$ mixed oxide catalyst prepared by the co-precipitation method and the noble metal catalyst (1wt% $Pt/{\gamma}-Al_2O_3$) were 82 and 81% at $150^{\circ}C$, respectively, whereas the highest CO conversion with the CuO-$CeO_2$ mixed oxide catalyst prepared by the sol-gel method was 90% at the same temperature. This indicates that the catalyst prepared by the sol-gel method shows higher catalytic activity than the catalysts prepared by the co-precipitation method and the noble metal catalyst. From the CO-TPD experiment, it was found that the catalyst having CO desorption peak at a lower temperature ($140^{\circ}C$) revealed higher catalytic activity.

Preparation by the double extraction process with preliminary neutron irradiation of yttria or calcia stabilised cubic zirconium dioxide microspheres

  • Brykala, Marcin;Walczak, Rafal;Wawszczak, Danuta;Kilim, Stanislaw;Rogowski, Marcin;Strugalska-Gola, Elzbieta;Olczak, Tadeusz;Smolinski, Tomasz;Szuta, Marcin
    • Nuclear Engineering and Technology
    • /
    • v.53 no.1
    • /
    • pp.188-198
    • /
    • 2021
  • A modern approach to nuclear energy involves reprocessing like transmutations of spent nuclear fuel products to reduce their radiotoxicity and time needed for their storage. For this purpose, they are immobilized in inert matrices made of zirconia and can be "burned" in fast neutron reactor or Accelerator Driven System. These matrices in spherical form can be obtained by sol-gel process. The paper presents a method of microspheres fabrication based on the combined Complex Sol-Gel Process and double extraction process consisting in the preparation of zirconium-ascorbate sol and simultaneous extraction of water and nitrates. The procedure allows obtaining gel microspheres with a diameter of 50 ㎛, which after heat treatment are processed into the final product. The synthesis of zirconia microspheres with Yttrium by internal gelation process is well known for over a decade now. However, the explanation and characterization of synthesis of such material by extraction of water process is rarely found. Parameters such as: pH, viscosity, shape, sphericity and crystal structure have been determined for synthesized products and semi-products. In addition, preliminary research consisting in irradiation of the obtained materials in fast and thermal neutron flux was carried out. The obtained results are presented and described in this work.

Preparation of Photochromic Coating Films Containing Spiropyran by Sol-Gel Method (Sol-Gel법에 의해 Spiropyran을 함유한 광 변색 코팅 막의 제조)

  • Jeong, Sang Hyeok;Cho, Kyung In;Song, Ki Chang
    • Korean Chemical Engineering Research
    • /
    • v.46 no.1
    • /
    • pp.112-117
    • /
    • 2008
  • Organic-inorganic hybrid solutions were prepared via sol-gel method using glycidoxypropyl trimethoxysilane (GPTMS) and methyl triethoxysilane (MTES) as starting precursors at a molar ratio of 1:1. The photochromic coating solutions were prepared by mixing the solutions of photochromic dye (spiropyran) dissolved in ethylacetate (EA) with the organic-inorganic hybrid solutions. Photochromic films were prepared on polycarbonate substrate by spin coating and cured for 2 h at $100^{\circ}C$. The resulting films exhibited a reversible color change upon irradiation with UV light. The photochromic properties of the films showed that the color-fading speed increases with increasing the EA content in the coating solutions.

Preparation of Alumina Sol Coated BOPP Composites and Their Gas Permeation Characteristics (Alumina Sol을 코팅한 BOPP 복합체의 제조 및 기체 투과 특성)

  • Hong, Seong-Uk;Oh, Jae-Won;Ko, Young-Deok;Song, Ki-Chang
    • Membrane Journal
    • /
    • v.19 no.1
    • /
    • pp.19-24
    • /
    • 2009
  • Sol-gel process is relatively simple, easy to use, cheap to install, and results in thin coating layers with superior physical and gas barrier properties. Films coated by the sol-gel process can be used as insulating films or packaging films for foods, chemicals, drugs, and beverages, etc. In this study, alumina sol was synthesized from aluminum isopropoxide and silane coupling agent was added to make coating solutions. In addition, biaxially oriented polypropylene (BOPP) was coated using several alumina sol solutions and their oxygen permeabilities were measured. The experimental results indicate that in the best case, the oxygen permeability of coated film was reduced by 85% compared to that of pure BOPP.

The Preparation of Sol-Gel Derived Aminoalkoxysilane Films and its Application for Oxygen Barrier (솔-젤법을 이용한 aminoalkoxysilane 산소차단필름의 제조)

  • Kim, Hyun-Joon
    • Journal of the Semiconductor & Display Technology
    • /
    • v.5 no.3 s.16
    • /
    • pp.17-21
    • /
    • 2006
  • The oxygen barrier films were formed on poly(ethylene terephthalate) (PET) substrate by a sol-gel process using aminoalkoxysilanes. The coating layers were characterized by FT-IR and SEM. The oxygen permeability coefficients of coating films were measured by variable volume method, and then the influences of solvent ratio in sol and film drying temperature on the oxygen barrier properties were investigated. The aminoalkoxysilane coating films exhibited much higher oxygen barrier properties than PET film. The oxygen permeability coefficient of the film coated with each of APTEOS and APTMOS was measured to be $2.96{\times}10^{-6}$ and $3.05{\times}10^{-5}\;GPU$, respectively, while that of PET film was $1.16{\times}10^{-4}\;GPU$.

  • PDF